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| From | Kragen Javier Sitaker <kragen@canonical.org> |
|---|---|
| Newsgroups | comp.arch |
| Subject | Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) |
| Date | 2026-09-02 13:52 -0300 |
| Organization | Primarily biological and memetic |
| Message-ID | <871pbb8ujd.fsf@debian> (permalink) |
| References | (1 earlier) <116d89d$27baf$1@paganini.bofh.team> <2026Aug24.095510@mips.complang.tuwien.ac.at> <87a4q0afu7.fsf_-_@debian> <20260901143106.00006dd7@gmail.com> <1788314691-5857@newsgrouper.org> |
MitchAlsup <user5857@newsgrouper.org.invalid> writes:
> John Ames <commodorejohn@gmail.com> posted:
>> The idea I had last time I dabbled with this stuff was to extend the
>> basic add/subtract instructions with an option to save the carry/borrow
>> value in another GPR, instead - but I never gave any thought to how to
>> represent overflow that way. Hmm.
>
> That is what CARRY does. The Rd register in CARRY supplies a register
> used to carry the additional values from calculation to calculation.
> The Immediate in CARRY selects which instruction consume Rd {i},
> which instructions generate the next Rd {o} and which do both {io}
> and which do neither {}.
This is on your 66000?
Kragen
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adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-01 17:15 -0300
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) John Ames <commodorejohn@gmail.com> - 2026-09-01 14:31 -0700
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) BGB <cr88192@gmail.com> - 2026-09-01 17:18 -0500
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-09-02 02:04 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) John Ames <commodorejohn@gmail.com> - 2026-09-02 08:23 -0700
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-11 13:48 -0300
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-09-11 18:03 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-02 13:52 -0300
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-09-02 17:41 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-09-09 11:16 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) MitchAlsup <user5857@newsgrouper.org.invalid> - 2026-09-02 01:53 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) EricP <ThatWouldBeTelling@thevillage.com> - 2026-09-05 12:08 -0400
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-09-09 13:36 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-09-09 10:50 +0000
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) Paul Rubin <no.email@nospam.invalid> - 2026-09-09 22:10 -0700
Re: adding overflow and carry to every GPR (was Re: OT: Epic RISC-V rant) Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-11 14:28 -0300
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